Microelectromechanical systems (MEMS) resonators and related apparatus and methods
Devices having piezoelectric material structures integrated with substrates are described. Fabrication techniques for forming such devices are also described. The fabrication may include bonding a piezoelectric material wafer to a substrate of a differing material. A structure, such as a resonator, may then be formed from the piezoelectric material wafer.
1. An apparatus, comprising:
a suspended, substantially rectangular, piezoelectric microelectromechanical systems (MEMS) resonator coupled to a first substrate, the suspended piezoelectric MEMS resonator comprising an active layer of a piezoelectric material, a multi-layered temperature compensation structure coupled to a first surface of the active layer, and a plurality of electrodes disposed adjacent a second surface of the active layer opposite the first surface, wherein the piezoelectric MEMS resonator is configured to exhibit in-plane Lamb wave vibration in response to application of an electric field thereto by the plurality of electrodes; and
a cap bonded to the MEMS resonator via a eutectic bond, the cap lacking integrated circuitry and forming a hermetic seal with the first substrate.
2. The apparatus of claim 1 , wherein the cap is formed of an insulating material, and wherein the apparatus further comprises through-silicon vias (TSVs) in the cap and configured to conduct electrical signals between the piezoelectric MEMS resonator and circuitry formed external to the apparatus.
3. The apparatus of claim 2 , wherein the insulating material comprises glass.
4. The apparatus of claim 2 , wherein the insulating material comprises ceramic.
5. The apparatus of claim 1 , wherein the cap is a silicon substrate.
6. The apparatus of claim 5 , wherein the silicon substrate is a thinned silicon substrate.
7. The apparatus of claim 5 , wherein the silicon substrate is an non-thinned silicon substrate.
8. The apparatus of claim 1 , wherein the cap comprises an integrated heater.
9. The apparatus of claim 1 , wherein the cap comprises an integrated thermistor.
10. The apparatus of claim 1 , wherein the cap comprises no active circuitry.
11. The apparatus of claim 1 , wherein the cap comprises an access hole formed therein.
12. The apparatus of claim 1 , wherein the eutectic bond is an Al—Ge eutectic bond.
13. The apparatus of claim 1 , coupled to an external circuit configured to control operation of the piezoelectric MEMS resonator.
14. The apparatus of claim 13 , wherein the cap is formed of an insulating material, and wherein the apparatus further comprises through-silicon vias (TSVs) in the cap and configured to conduct electrical signals between the piezoelectric MEMS resonator and circuitry formed external to the apparatus.
15. The apparatus of claim 1 , further comprising a heating element and a temperature sensor integrated with the MEMS resonator.
16. The apparatus of claim 1 , further comprising a heating element and a temperature sensor integrated with the cap.